In some laser radar systems, a translation of a corner cube is used to focus a measurement beam at various target distances. A corner cube can be advantageous because its performance is not strongly impacted by corner cube tilts, and corner cube surfaces are rigidly fixed so that reflection directions are unlikely to change due to changes in the corner cube. Unfortunately, corner cubes are relatively heavy, expensive, and occupy a considerable volume, and focusing systems that do not require larger corner cubes would be preferred.